The present invention relates to a cleaning solution and a cleaning method for a component of a semiconductor processing apparatus. More specifically, the present invention relates to a cleaning solution and a cleaning method for removing a byproduct deposited on a component of a semiconductor processing apparatus and derived from the decomposed substances of a process gas containing C and F. Semiconductor processing here means a variety of processes executed to manufacture semiconductor devices on target substrates, such as semiconductor wafers or LCD substrates, and structures including interconnections and electrodes connected to semiconductor devices by forming semiconductor layers, insulating layers, conductive layers, and the like in predetermined patterns on the target substrates.
Etching is one of the main semiconductor processes. Etching is performed using an etching apparatus having a process chamber in which an upper electrode is arranged to oppose a lower electrode (susceptor). To etch a silicon oxide (SiO2) film on the surface of a semiconductor wafer in this etching apparatus, a wafer serving as the target substrate is placed on the lower electrode. In this state, RF power is supplied to the lower electrode while a fluorocarbon-based (including a hydrofluorocarbons-based) process gas, i.e., CF-based process gas, such as CF4, is introduced into a process chamber. With this operation, the process gas is converted into a plasma, and the silicon oxide film is anisotropically etched by this plasma.
In this etching, characteristics, such as etching anisotropy and etching rate, are controlled using the CF-based deposit produced from the decomposed substances of the process gas. More specifically, the chemical and physical actions given to the silicon oxide film from the active species and ions from the plasma are controlled by the CF-based deposit on a portion to be etched, e.g., the inner surface of a contact hole. That is, CF-based products are essential in the etching process, and CF-based byproducts also deposit on various components in the process chamber.
For example, some etching apparatus of this type includes a clamp ring for fixing a target substrate, e.g., a semiconductor wafer, on a lower electrode and a focus ring for causing a plasma produced in the process chamber to impinge on the wafer in a desired state. A baffle plate is disposed around the lower electrode to adjust the conductance in the process chamber. A wall protecting member is disposed along the side wall in order to protect the inner surface of the process chamber. The above-mentioned CF-based byproducts cumulatively deposit on all these components.
A deposit made of a CF-based byproduct peels off when it reaches a certain thickness, thereby producing particles. This degrades the yield of semiconductor devices. For this reason, before the deposit peels off, these components must be cleaned to remove the deposit. To reduce the downtime of the apparatus, components on which a CF-based byproduct readily deposits are generally built from components that are easy to exchange. Components with a CF-based byproduct deposited thereon, after use for a predetermined period of time, are removed from the process chambers, and new cleaned equivalent components are attached to the corresponding positions.
Conventionally, components with a deposit of a CF-based byproduct attached thereto are removed and dipped in a fluorine-based solvent (e.g., perfluorocarbon: PFC) or acetone in order to swell the deposit. Then, to peel the deposit off, the components are ultrasonically vibrated in pure water and thus cleaned.
In the above cleaning, since the CF-based byproduct is removed by swelling and peeling the deposit, a very large number of fine CF-based byproduct particles remain on the components on the microscopic level even after they are cleaned. The fine CF-based byproduct particles are peeled off by RF discharge and deposit on the wafer in the form of particles.
In etching of this type, so-called seasoning for processing a number of dummy wafers (20 to 25 dummy wafers) is generally performed after the cleaned components are mounted in the process chamber. This seasoning amounts to coating the fine residue remaining on the components with a new CF-based byproduct, thereby suppressing generation of particles below a prescribed value. The time (1 to 2 hours) for processing the dummy wafers substantially accounts for downtime of the apparatus.
The use of PFC or acetone requires several days to clean the components with the deposit made of a CF-based deposit attached thereto. This results in very low work efficiency. In addition, PFC has a global warming coefficient much larger than CO2, although PFC is chemically stable and easy to handle. Acetone is a material toxic to man and having a low flash point. Acetone therefore requires sophisticated settings for use environment and much cost in storage and management.
The present invention has been made in consideration of the conventional problems described above, and an object thereof is to provide a cleaning solution and a cleaning method for a component of a semiconductor processing apparatus, in which a CF-based byproduct can be efficiently and reliably removed.
Another object of the present invention is to provide a cleaning solution and a cleaning method for a component of a semiconductor processing apparatus, which are highly safe and hardly cause destruction of terrestrial environment.
According to the first aspect of the present invention, there is provided a cleaning solution for removing a byproduct derived from a decomposed substance of a process gas containing C and F, and deposited on a component in a process chamber of a semiconductor processing apparatus for subjecting a target substrate to a semiconductor process with the process gas, the cleaning solution containing N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, and a surfactant.
According to the second aspect of the present invention, in the cleaning solution of the first aspect, an alkali metal content is less than 10 ppb.
According to the third aspect of the present invention, the cleaning solution of the first or second aspect further contains water.
According to the fourth aspect of the present invention, in the cleaning solution of the third aspect, the water is contained at a content of 5 to 20 wt %.
According to the fifth aspect of the present invention, in the cleaning solution according to any one of the first to fourth aspects, the surfactant is contained at a content of 0.1 to 1.0 wt %.
According to the sixth aspect of the present invention, in the cleaning solution according to the fifth aspect, the surfactant contains fluorine.
According to the seventh aspect of the present invention, in the cleaning solution according to any one of the first to sixth aspects, a total content of the N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether is 80 to 90 wt %, and a ratio of a content of the N-methyl-2-pyrrolidone to the total content of the N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether is 0.75 to 0.95.
According to the eighth aspect of the present invention, there is provided a cleaning method for removing a byproduct derived from a decomposed substance of a process gas containing C and F, and deposited on a component in a process chamber of a semiconductor processing apparatus for subjecting a target substrate to a semiconductor process with the process gas, the method comprising the steps of: removing the component from the process chamber; and dipping the component in a bath of the cleaning solution according to any one of the first to seventh aspects.
According to the ninth aspect of the present invention, in the cleaning method according to the eighth aspect, the component is dipped in the bath of the cleaning solution while the component is stored in a cage with 500 to 100 meshes.
According to 10th aspect of the present invention, in the cleaning method according to the eighth or ninth aspect, the component is dipped in the bath of the cleaning solution while a temperature of the cleaning solution is set at 50 to 80xc2x0 C.
According to the 11th aspect of the present invention, in the cleaning method according to any one of the eighth to 10th aspects, the semiconductor process comprises etching a layer consisting essentially of a silicon oxide on the target substrate by using the process gas.